Palo Alto Municipal Code § 16.11 Stormwater Pollution Prevention

The purpose of this chapter is to control and limit stormwater runoff pollution by preventing pollutants from entering the City of Palo Alto storm drain system and receiving waters, including the San Francisco Bay (bay) and local creeks, marshes, wetlands and other natural habitats, as well as to protect human health and the environment. This chapter is enacted and shall be implemented in a manner consistent with the Porter-Cologne Water Quality Control Act (Water Code Section 13000 et seq.) and the Federal Clean Water Act (33 U.S.C. Section 1251 et seq.) (CWA), and the requirements of the Municipal Regional Stormwater Permit (MRP) issued by the California Regional Water Quality Control Board, San Francisco Bay-Region 2 (Regional Water Board), as amended from time to time. This chapter is intended to be no less stringent than the MRP and in some respects may be more stringent than regional, state or federal regulations, rules, orders and policies. The city intends to update and modify this chapter as needed to continue to meet Regional Water Board requirements and provide a program for protection of the bay and other receiving waters. If any provision of this chapter conflicts with the MRP, as amended or updated, the more stringent and environmentally protective provision shall apply.

(Ord. 5671 § 2 (part), 2025)

The following words and phrases, whenever used in this chapter, shall be as defined herein. Words and phrases used in this chapter not otherwise defined in this section shall be as defined, interpreted or used in the MRP in effect or, if not used in the MRP, so as to give this chapter its most reasonable application.

“Applicant” means any person that submits an application for a planning and land use entitlement or building permit from the City of Palo Alto.

“Best management practices” or “BMPs” mean a combination of general good housekeeping practices, pollution prevention and educational practices, operations and maintenance procedures, and other practices and requirements to prevent or reduce to the maximum extent practicable non-stormwater discharges directly or indirectly to the storm drain system or receiving waters. Sources of industry-standard BMPs include but are not limited to the Santa Clara Valley Urban Runoff Pollution Prevention Program, the California Stormwater Quality Association Stormwater Best Management Practice Handbook, the California Department of Transportation Construction Site Best Management Practices Manual, and the MRP. Unless otherwise stated, reference to BMPs generally means non-structural BMPs as described in this definition.

“Building” means any structure used or intended for supporting or sheltering any use or occupancy.

“Building permit” means the authorization provided by the city to build/construct one or more buildings.

“CASQA” means California Stormwater Quality Association, a professional member association dedicated to the advancement of stormwater quality management through collaboration, education, implementation guidance, regulatory review, and scientific assessment.

“City” or “The City” means City of Palo Alto, California.

“Construction activity” means any earth- or soil-disturbing activity, including, but not limited to, clearing, grading, paving, landscaping, excavation, stockpiling, material storage, and disturbances to land or ground such as building of a structure, and demolition or removal of structures or paved surfaces.

“Construction site” means any site where construction activity occurs.

“Contamination” shall have the same meaning as defined in California Water Code Section 13050, as amended from time to time.

“Contiguous” means touching or sharing a border and includes project areas interrupted by cross streets or intersections.

“Detached single-family home project” means the building of one single new house or the addition and/or replacement of impervious surface to one single existing house, which is not part of a larger plan of development.

“Development project” means new construction or redevelopment of any public or private project involving construction activity and within the planning and building authority of the city.

“Director” means the Director of Public Works of the City of Palo Alto and his or her duly authorized designees.

“Discharge” when used as a verb, means to allow a stormwater or non-stormwater substance to enter the storm drain system or a receiving water from any activity or operation. When used as a noun, “discharge” means the stormwater or non-stormwater discharge that is released or conveyed.

“Discharger” means any person who causes or permits a discharge.

“EPA” or “U.S. EPA” means the Environmental Protection Agency of the United States of America.

“Full trash capture device or system” means a treatment control, or series of treatment controls, that traps all particles that are five mm or greater and has a design treatment capacity that is either: a) of not less than the peak flow rate, Q, resulting from a one-year, one-hour storm in the subdrainage area, or b) appropriately sized to, and designed to carry at least the same flows as, the corresponding storm drain. The device(s) shall also have a trash reservoir large enough to contain a reasonable amount of trash safely without overflowing trash into the overflow outlet between maintenance events.

“Green stormwater infrastructure” or “GSI” means infrastructure that uses vegetation, soils, and natural processes to manage stormwater runoff. At the scale of a city or county, GSI refers to the patchwork of natural areas that provides habitat and manages smaller storms, cleaner air, and cleaner water and eliminates street ponding. At the scale of a neighborhood or project site, GSI refers to stormwater management systems that mimic the natural hydrologic cycle by soaking up and storing water.

“Hazardous material” means any material designated as hazardous by Title 17 of this Code.

“Hazardous waste” means any material designated as a hazardous waste by applicable federal, state or local regulations.

“Illicit connection” means any device, artifice, method or connection that conveys non-stormwater to the storm drain system. Examples may include connections from interior floor drains, HVAC systems, industrial processes, sinks, and toilets. An illicit connection does not include methods of conveyance of groundwater during construction activities in compliance with this code and as approved by the Director.

“Illicit discharge” means any discharge that is prohibited under local, state, or federal statutes, ordinances, codes, or regulations and this chapter. Illicit discharges do not include discharges that are exempt or conditionally exempt under the MRP, regulated by a NPDES permit other than the MRP, or authorized by the Executive Officer of the Regional Water Board or the Director.

“Impervious surface” means land that has been modified to reduce or remove the land's natural ability to absorb and infiltrate rainfall. Impervious surfaces include, but are not limited to, rooftops, pavement, sidewalks, walkways, patios, driveways, and parking lots where such surfaces are not constructed with pervious materials and/or

are not designed to infiltrate stormwater.

“Joint stormwater treatment facility” is a stormwater treatment facility built to treat the combined runoff from two or more regulated projects located adjacent to each other.

“Loading dock” means a raised or lowered area of a facility designed to accommodate a truck, trailer or other large delivery vehicle for the loading and unloading of equipment or materials. A loading dock does not include such an area where the deliveries are limited solely to furniture and non-electronic office supplies.

“Low impact development” or “LID” is a land planning and engineering design approach with a goal of reducing stormwater runoff and mimicking a site’s predevelopment hydrology by minimizing disturbed areas and impervious cover and infiltrating, storing, detaining, evapotranspiring, and/or biotreating stormwater runoff close to its source, or onsite.

“Mobile business” means a business whose operations may produce or result in the production of pollutants and that does not operate from a permanent structure but instead provides mobile services during particular time periods or upon request at temporary locations. Types of services include cleaning or power washing of vehicles, structures, windows, or parking lots; engine or equipment degreasing; acid cleaning of unpainted trucks or containers; steam cleaning; carpet cleaning; dental and medical care; vehicle repair, servicing, fueling and cleaning; and pet services (including grooming, veterinary care and other miscellaneous services).

“Municipal Code” means the ordinances and laws adopted and enforced by the City of Palo Alto.

“Municipal regional stormwater permit” or “MRP” means the most recently adopted San Francisco Bay Area municipal regional stormwater permit, a multi-countywide municipal stormwater NPDES permit issued by the California Regional Water Quality Control Board, San Francisco Bay Region-Region 2 (Regional Water Board) to regulate discharges from municipalities and local agencies in Alameda, Contra Costa, San Mateo, and Santa Clara counties, and the cities of Fairfield, Suisun City, and Vallejo.

“Non-stormwater discharge” means any discharge that is not entirely composed of stormwater. Non-stormwater discharges include, but are not limited to, polluted groundwater, any pollutant, discharges allowed under an NPDES permit, or an illicit discharge.

“NPDES” means National Pollutant Discharge Elimination System, which is a national program for issuing, modifying, revoking and reissuing, terminating, monitoring and enforcing permits, and imposing and enforcing pretreatment requirements, under Sections 307, 402, 318, and 405 of the Federal Clean Water Act.

“PCB screening assessment” means a report prepared by an applicant for a demolition permit containing any information and data (investigations, reports, soil samples, laboratory results, construction site controls, etc.) reasonably required by the Director regarding the presence of polychlorinated biphenyls (PCBs).

“Permit” means any authorization issued by the city to carry out an action or activity according to the city’s Municipal Code, rules, and regulations.

“Person” means any individual, partnership, firm, company, corporation, association, joint venture, joint stock company, trust, estate, governmental entity, or any other legal entity; or their representatives, agents, or designees.

“Pervious” means capable of allowing water to infiltrate below the surface. Pervious materials may include, but are not limited to, permeable interlocking concrete pavers, permeable pavers, pervious concrete and porous asphalt.

“Planning and land use entitlement” means approval provided by the city to develop a building (or buildings) or a piece of land for a specific use according to the city’s development standards, rules, and regulations.

"Pollutants” or “pollutant” means those substances associated with stormwater runoff that may cause or contribute to the degradation of water quality of receiving waters and are harmful to aquatic life, human health and the environment. Pollutants commonly associated with stormwater runoff include, but are not limited to, total suspended solids; sediment; pathogens (e.g., bacteria, viruses, protozoa); heavy metals (e.g., copper, lead, zinc, and cadmium); petroleum products and polynuclear aromatic hydrocarbons; synthetic organics (e.g., pesticides, herbicides, and PCBs); nutrients (e.g., nitrogen and phosphorus fertilizers); oxygen-demanding substances (e.g., decaying vegetation and animal waste); litter and trash.

"Pollution" means the presence, introduction or discharge into a receiving water of a pollutant that has harmful or poisonous effects on aquatic life, ecological habitat, natural processes of creeks and waterbodies, public health and the environment.

“Receiving water” means waters of the state, as defined by the Porter-Cologne Water Quality Control Act. Receiving waters include but are not limited to creeks, marshes, wetlands, shorelines, estuaries, and bays.

“Redevelopment” means any land-disturbing activity that results in the creation, addition, or replacement of exterior impervious surface area on a site on which some past development has occurred. This category includes projects on public or private land that fall under the planning and building authority of the city.

"Refuse" means and includes compostable materials, recyclable materials, and solid waste. Solid waste means solid and semisolid wastes, generated in or upon, related to the occupancy of, remaining in or emanating from residential premises or commercial premises including but not limited to garbage, trash, rubbish, ashes, and industrial wastes.

“Refuse management and containment area” means an area such as a room located inside a building or an enclosed structure located outdoors to keep, manage and contain compostable, recyclable and solid waste.

“Regional Water Board” or “Water Board” means the California Regional Water Quality Control Board, San Francisco Bay-Region 2.

“Regulated project” means a project described in Chapter 16.11.150, “Regulated Projects.”

“Remodel” is an extension or modification of an existing structure. This may include a one or second-story addition that increases the footprint of the structure or an interior reconfiguration.

“Responsible party” means any person who owns, operates, or manages a property, business, facility, or site, or who is otherwise responsible for the activities thereon or the person whose action or omission causes or results in the violation of this chapter.

“Sanitary sewer system” means the collection system, all sewers, treatment plants and other facilities owned or operated by the city for carrying, collecting, storing, treating, reclaiming and disposing of sanitary sewage and industrial wastes (as defined in Section 16.09.015).

“SCVURPPP” or “Santa Clara Valley Urban Runoff Pollution Prevention Program” means an association of 15 agencies in Santa Clara Valley that share a common NPDES MRP to discharge to south San Francisco Bay. Member agencies (also referred to as co-permittees) include the cities or towns of Campbell, Cupertino, Los Altos, Los Altos Hills, Los Gatos, Milpitas, Monte Sereno, Mountain View, Palo Alto, San Jose, Santa Clara, Saratoga, and Sunnyvale, Santa Clara County, and the Santa Clara Valley Water District (Valley Water).

“Sewage” means the wastewater of the community derived from residential, agricultural, commercial, or industrial sources, including domestic sewage, and industrial wastewater, which is required to be conveyed to the sanitary sewer system.

“Site design measure” means a site planning technique to conserve natural spaces and/or limit the amount of impervious surface at development and redevelopment projects in order to minimize runoff and the transport of pollutants in stormwater runoff.

“Source control measure” means any BMP that aims to prevent runoff pollution by reducing the potential for contact with rainfall runoff at the source of pollution. Source control BMPs minimize contact between pollutants and stormwater runoff.

“Special projects” are a type of regulated project that meets criteria based on size, land use type, and density per the MRP. These projects are typically located in high density areas and are centered around transit-oriented development. If criteria determined by the MRP are met, projects are entitled to incentive LID treatment reduction credits approved by the Water Board.

“Storm drain system” means the storm drain facilities owned, managed, or operated by the city by which stormwater is collected and/or conveyed to receiving waters, including but not limited to streets and roads, gutters, curbs, inlets, piped storm drains, parking lots, pumping facilities, retention and detention basins, natural and human-made or altered drainage channels, reservoirs, and other drainage structures which are within the city’s jurisdiction. The storm drain system also includes pipes, underground and surface conveyances, and other components on private property and other property within the city’s limits not owned by the city that connect and/or route stormwater and stormwater runoff to the city’s storm drain system.

“Stormwater” means any surface flow, runoff, and drainage consisting entirely of water that originates from precipitation events.

“Stormwater runoff” means flow that is created when precipitation falls on impervious surfaces or compacted pervious surfaces that do not allow water to infiltrate into the ground.

“Stormwater run-on” means flow that runs across impervious surfaces or compacted pervious surfaces from one property to another or from one use on a property to another.

“Stormwater treatment measure” means any engineered, non-mechanical or constructed system designed to remove pollutants from stormwater runoff by simple gravity settling of particulate pollutants, filtration, infiltration, biological uptake, media adsorption or any other physical, biological, or chemical process.

“Structural retrofit best management practices” or “structural retrofit BMPs” means a retrofit to a structure, fixed feature, or property to prevent or minimize the potential of a non-stormwater discharge to the storm drain system or receiving waters, in association with an enforcement action due to noncompliance with this

chapter.

(Ord. 5671 § 2 (part), 2025